% of patients with treatment failure defined as: absence of clinical response at D7 or absence of remission without steroids at D98 or relapse or severe adverse event leading to treatment interruption or colectomy or fatality between D0 and D98 [ Time Frame: Day 7 ] [ Designated as safety issue: No ]

Original Primary Outcome Measures ICMJE (submitted: October 9, 2007)

% of patients with treatment failure defined as: absence of clinical response at D7 or absence of remission without steroids at D98 or relapse or severe adverse event leading to treatment interruption or colectomy or fatality between D0 and D98

Cyclosporine 2mg/kg/day intravenous for 7 days then Neoral 4mg/kg/day orally for 3 months.

Infliximab 5mg/kg at weeks 0, 2 and 6

Other Names:

Cyclosporine (IV)= Brand Name = Sandinuum

Cyclosporine (PO)= brand name = Neoral

Infliximab (IV)= brand name= Remicade

Study Arm (s)

Active Comparator: CICLO

Cyclosporine will be administered by continuous intravenous infusion at the initial dose regimen of 2mg/kg per day.

After 24 hours of treatment, cyclosporine trough level will be measured and the dose adapted in order to obtain a cyclosporinaemia level between 150 and 250 ng/ml. Cyclosporinaemia will be reassessed every 48 hours for the duration of the continuous intravenous treatment.

Intervention: Drug: CYCLOSPORINE VS INFLIXIMAB

Active Comparator: INFLIXIMAB

INFLIXIMAB (REMICADE) Infliximab in the form of a freeze-dried compound is conditioned in 100mg vials. Treatment will first be reconstituted in 250ml isotonic saline solution, and slowly infused at the dose of 5mg/kg in 2 hours.

In patients with clinical response at D7 (Lichtiger Index score < 10 for 2 consecutive days), two additional infliximab infusions will be administered at the dose of 5mg/kg at D14 and D42.